This invention relates to metal cutting and in particular to methods and apparatus for performing relatively large surface area cutting operations on metal plates using relatively low power equipment.
In general, performing large surface area cutting operation on metal plates requires equipment having a size and power proportionate to the size of the cutting operation to be produced. Various attempts have been made to provide methods and apparatus for performing large surface area cutting operations utilizing relatively low power equipment. In one such method and apparatus, a cutter blade is positioned transversely in a slot in an elongated pilot holder at a location spaced axially from the leading end of the holder so as to define a pilot portion on the holder ahead of the cutter blade; a pilot hole having a diameter substantially corresponding to the diameter of the pilot portion of the pilot holder is provided in the plate member to be cut; the pilot portion of the pilot holder is positioned in the pilot hole; and the pilot holder is advanced axially to move the cutter blade into the plate member and form a spot face or counterbore with respect to the pilot hole. This arrangement is effective in performing relatively large surface area operations on metal plate material but the diameter of the spot face, holes, or counterbores that can be performed with this arrangement is still significantly limited by the limitations of the associated power equipment and by the strength limitations of the blade. The described arrangement has the further disadvantage that, when it is desired to form a counterbore or spot face on both sides of the metal plate, it is necessary to utilize a first cutter blade to work on one face of the plate and another cutter blade having a backward cutting edge design to work on the other face of the plate.